The invention relates to a method for reducing reflection when operating a head-up display of a motor vehicle. The head-up display in this case comprises a covering disk element and a dimming element, wherein the dimming element is designed to dim a light beam of ambient light of the motor vehicle deflected by the covering disk element, and it can include for example a mirror bank.
Heads-up displays are used in motor vehicles in order to provide information for the driver directly in his field of view. A head-up display is a display device that projects digital graphic information, which is to say a virtual image, on a reflecting surface in a motor vehicle, for example on a windshield, in the field of view of a user, so that the user can maintain his head position and the view direction. In this case, differently designed mirrors place the virtual image visible on the road.
In order to provide a sufficient protection for a head-up display and for the associated image information against reflections, which can be caused for example by sun beams that may be deflected by the covering disk element and by the windshield into the eyes of the user, a mirror bank is provided on the head-up display that shields the reflection area in the vicinity of the eye point, which is to say around the eyes. For this purpose, the reflection-free area around the eye point is defined, which is to say as the area to be kept free of deflected light. The inner side of the mirror bank is mostly configured with a matte black design in order to absorb light. The covering disk element, which can comprise for example a cover disk or a cover plate, serves in this case to protect the head-up display, creating a light trap together with the mirror bank.
In this manner, the eye point, the cover disk and the disk shape of the motor vehicle exert an influence on the position and the direction in which the mirror bank is used.
In order to deflect ambient light of a motor vehicle, DE 10 2008 015 997 A1 proposes a head-up display in which the virtual image to be projected is passed through a cylindrical lens on the windshield prior to the projection. The lens is inclined towards the projection light to deflect the ambient light.
From US 2011/0007399 A1 is known a head-up display, which has an optical system that is provided with a predetermined level of chromaticization. This results in a reduction of the sunlight on the windshield. External light outside the car is thus reflected or deflected through a surface of a prism in order to prevent occurrences or formation of a ghost image through the external light.
However, the integration of the head-up display under specified technical conditions is often associated concessions with respect to the technical design. So for example, the heads-up display and in particular the mirror bank are in many cases fully or partially visible behind the area of the hood. This is not desirable from the viewpoint of the visibility for the driver and from the viewpoint of the technical design because the driver then looks into a kind of a hole. This is due to a negative position of the mirror bank and to the matte black color of the surface. Although the construction based on prior art can be perceived by the driver as disturbing, so far it has not been possible to accommodate the head-up display in another space suitable for installation.